A high vacuum MEMS sensitive structure packaging structure and method

Abstract

The present invention discloses a high vacuum MEMS sensitive structure packaging structure and method, the packaging structure includes a base, a shell and a vacuum gauge; the vacuum gauge includes a MEMS structure, a metal seat and a circuit board, the base is provided with a through hole, the first end of the base corresponds to the position of the through hole as a vacuum chamber interface that can be connected to a vacuum chamber, the metal seat is connected to the second end of the base by parallel seam welding, and the MEMS structure is located in the through hole; an accommodation cavity is formed between the shell and the base, the circuit board is located in the accommodation cavity, the second end of the shell is provided with a host computer connector, and the circuit board is electrically connected to the host computer connector. The present invention is applied to the fields of vacuum measurement and electrical connection elements, not only has high applicability, can be adapted to various types of MEMS vacuum gauges, but also has a strong and reliable sealing effect, is suitable for high vacuum environments, can achieve extremely low gas permeability, and can maintain excellent airtightness for a long time.

Description

Technical Field

[0001] The invention relates to the technical field of vacuum measurement and electrical connection elements, and in particular to a high vacuum MEMS sensitive structure packaging structure and method. Background Art

[0002] With the continuous advancement of technology, the requirements for vacuum degree in a large number of industries and equipment are constantly increasing, such as infrared detection, ion beam adjustment, etc. In order to accurately measure the vacuum degree of the environment, vacuum gauges have been widely studied at home and abroad in recent years. Among them, the tube shells used to package vacuum gauges are also quite diverse.

[0003] At present, vacuum gauges can be divided into Pirani gauges, capacitance film gauges, resistance gauges, resonance gauges and ionization gauges. According to different working principles, the first four types of vacuum gauges can be manufactured by MEMS technology. They have been widely studied and applied due to their small size and low power consumption. However, MEMS vacuum gauges are not easy to operate during testing due to their small size, so it is very necessary to design a test package shell. The sealing method of the vacuum gauge is crucial to ensure its measurement accuracy and long life. At present, most vacuum gauges use O-rings or soft pads for airtight isolation, which is easy to install, low cost, and can adapt to a certain degree of movement and temperature changes. However, they will lose elasticity over time and changes in the environment, resulting in leakage. At the same time, the gas permeability of the material is high and is not suitable for high vacuum environments. Summary of the invention

[0004] In view of the deficiencies in the above-mentioned prior art, the present invention provides a high-vacuum MEMS sensitive structure packaging structure and method, which is not only highly applicable and can be adapted to various types of MEMS vacuum gauges, but also has a very strong and reliable sealing effect, is suitable for high vacuum environments, can achieve extremely low gas permeability, and can maintain excellent airtightness for a long time.

[0005] To achieve the above-mentioned object, the present invention provides a high vacuum MEMS sensitive structure packaging structure, including a base, a housing and a vacuum gauge;

[0006] The vacuum gauge comprises a MEMS structure, a metal seat and a circuit board, and the MEMS structure and the circuit board are respectively located at the upper and lower ends of the metal seat;

[0007] The base is provided with a through hole, and the position of the first end of the base corresponding to the through hole is a vacuum chamber interface that can be connected to the vacuum chamber, the metal seat is fixedly connected to the second end of the base by parallel seam welding, and the metal seat covers the end of the through hole, and the MEMS structure is located in the through hole;

[0008] The first end of the shell is fixedly connected to the second end of the base, and a placement cavity is formed between the shell and the base. The circuit board is located in the placement cavity. The second end of the shell is provided with a host computer connector, and the circuit board is electrically connected to the host computer connector.

[0009] In one embodiment, a connecting thin plate is provided on the side of the metal seat, and the connecting thin plate is fixedly connected to the second end of the base by parallel seam welding. The connecting thin plate and the metal seat jointly cover the end of the through hole to achieve extremely low gas permeability, thereby ensuring air tightness and improving stability.

[0010] In one embodiment, the thickness of the connecting plate is 0.1 mm to 0.15 mm.

[0011] In one embodiment, the second end of the base is provided with an annular protrusion at a position corresponding to the periphery of the through hole;

[0012] The connecting thin plate is fixedly connected to the top of the annular protrusion by means of parallel seam welding.

[0013] In one embodiment, a groove is provided on the outer wall and / or inner wall of the bottom of the annular protrusion to reduce heat dissipation during parallel seam welding.

[0014] In one of the embodiments, a chamfered structure is provided at the inner ring contour of the top of the annular protrusion.

[0015] In one embodiment, a sealing structure is provided in the vacuum chamber interface to ensure airtightness of the connection between the base and the vacuum chamber.

[0016] In one embodiment, a step structure is formed on the inner wall of the vacuum chamber interface, and the bottom wall of the step structure faces the first end of the base;

[0017] The sealing structure comprises a sealing ring, a filter disc and a clamping stud, wherein a regular hexagonal through hole is opened in the center of the clamping stud, an external thread is processed on the outer side, and an internal thread matching the external thread is processed on the side wall of the step structure;

[0018] An annular groove is provided on the bottom wall of the step structure, the first end of the sealing ring is embedded in the annular groove, the filter disc is covered on the second end of the sealing ring, and the clamping stud is threadedly connected to the side wall of the step structure and clamps the filter disc.

[0019] In one embodiment, the metal seat is provided with a plurality of first through holes penetrating the metal seat, the circuit board is provided with second through holes corresponding to the first through holes one by one, and the first through holes are coaxial with the corresponding second through holes;

[0020] A metal column is provided in the first through hole, and the metal column is isolated and fixed to the hole wall of the first through hole by an insulating material;

[0021] The first end of the metal column is located in the through hole and connected to the MEMS structure through a lead, the second end of the metal column passes through the second through hole and is located above the circuit board, and the metal column is fixed to the circuit board by soldering.

[0022] To achieve the above object, the present invention further provides a high vacuum MEMS sensitive structure packaging method, using the above high vacuum MEMS sensitive structure packaging structure, the high vacuum MEMS sensitive structure packaging method comprises the following steps:

[0023] Place the sealing ring and filter on the bottom wall of the step structure in the vacuum chamber interface, and tighten the clamping studs to prevent the filter from falling off;

[0024] The MEMS structure is attached to a metal base with a metal column, and the pads on the MEMS structure are connected to the metal column through wires;

[0025] The connecting thin plate on the metal seat is welded to the annular protrusion at the second end of the base by parallel seam welding, so that the MEMS structure is connected only to the side with the filter and isolated from the gas influence on the other side;

[0026] Place the circuit board through the metal pillars and place it on the metal seat, and connect the metal pillars and the circuit board by soldering;

[0027] Connect the lead wire on the circuit board with the upper computer connector on the shell, and then connect and fix the first end of the shell with the second end of the base to assemble into a vacuum test gauge.

[0028] Compared with the prior art, the present invention has the following beneficial technical effects:

[0029] 1. The present invention isolates the MEMS structure of the vacuum gauge from the external environment by means of parallel seam welding, thereby providing a strong and reliable sealing effect, which can also be effectively applied in a high vacuum environment, achieves extremely low gas permeability, and can maintain excellent airtightness for a long time;

[0030] 2. The present invention has high applicability and can be adapted to various types of MEMS vacuum gauges. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0032] Figure 1 It is a front view of the packaging structure of the high vacuum MEMS sensitive structure in the embodiment of the present invention;

[0033] Figure 2 A cross-sectional view of a high vacuum MEMS sensitive structure packaging structure in an embodiment of the present invention;

[0034] Figure 3 It is a first isometric view of the high vacuum MEMS sensitive structure packaging structure in an embodiment of the present invention;

[0035] Figure 4 It is a second isometric view of the high vacuum MEMS sensitive structure packaging structure in an embodiment of the present invention;

[0036] Figure 5 It is a schematic diagram of a partial connection structure between a metal seat and a base in an embodiment of the present invention;

[0037] Figure 6 It is a schematic diagram of the partial connection structure between the circuit board and the metal column in an embodiment of the present invention.

[0038] Figure numbers: base 1, through hole 101, vacuum chamber interface 102, annular protrusion 103, groove 104, shell 2, MEMS structure 3, metal seat 4, connecting plate 401, metal column 402, circuit board 5, placement cavity 6, upper computer connector 7, sealing ring 8, filter 9, clamping stud 10.

[0039] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0040] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0041] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present invention are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0042] In addition, in the present invention, descriptions such as "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0043] In the present invention, unless otherwise clearly specified and limited, the terms "connection", "fixation", etc. should be understood in a broad sense. For example, "fixation" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, a physical connection, or a wireless communication connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0044] In addition, the technical solutions between the various embodiments of the present invention can be combined with each other, but it must be based on the fact that ordinary technicians in the field can implement it. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0045] like Figures 1 to 6The figure shows a high vacuum MEMS sensitive structure packaging structure disclosed in the present embodiment, which mainly includes a base 1, a shell 2 and a vacuum gauge. The vacuum gauge includes a MEMS structure 3, a metal base 4 and a circuit board 5, and the MEMS structure 3 and the circuit board 5 are respectively located at the upper and lower ends of the metal base 4, specifically: the MEMS structure 3 is located at the lower end of the metal base 4, and the circuit board 5 is located at the upper end of the metal base 4. The base 1 is a rotating body columnar structure as a whole. The base 1 is provided with a through hole 101 that penetrates the base 1 axially, and the first end of the base 1 corresponds to the position of the through hole 101 as a vacuum chamber interface 102. The vacuum chamber interface 102 is used to connect the vacuum chamber. The vacuum chamber interface 102 in the present embodiment is specifically a KF16 standard interface. The metal base 4 is fixedly connected to the second end of the base 1 by parallel seam welding, and the metal base 4 covers the end of the through hole 101, and the MEMS structure 3 is located in the through hole 101. The first end of the shell 2 is fixedly connected to the second end of the base 1, and a placement cavity 6 is formed between the shell 2 and the base 1. The circuit board 5 is located in the placement cavity 6. A host computer connector 7 is provided at the second end of the shell 2, and the circuit board 5 is electrically connected to the host computer connector 7. The host computer connector 7 in this embodiment is specifically a -J30 standard connector.

[0046] This embodiment isolates the MEMS structure 3 of the vacuum gauge from the external environment by means of parallel seam welding, so that it will not leak due to changes in time and temperature, thereby providing a strong and reliable sealing effect. It can also be effectively used in a high vacuum environment, achieving extremely low gas permeability, and can maintain excellent airtightness for a long time. At the same time, it also has high applicability and can be adapted to various types of MEMS vacuum gauges.

[0047] As a preferred embodiment, a connecting thin plate 401 is provided on the side of the metal seat 4, and the connecting thin plate 401 is fixedly connected to the second end of the base 1 by parallel seam welding. The connecting thin plate 401 and the metal seat 4 jointly cover the end of the through hole 101 to achieve extremely low gas permeability, ensure air tightness and improve stability, wherein the thickness of the connecting thin plate 401 is 0.1mm~0.15mm. If the metal seat 4 is directly fixedly connected to the base 1 by parallel seam welding, considering that the metal seat 4 itself has a large thickness, the edge of the metal seat 4 is difficult to melt during parallel seam welding, and it is difficult to form a weld, which affects the sealing effect. In this embodiment, the connecting thin plate 401 is provided to reduce the difficulty of edge melting caused by the thickness of the workpiece, thereby providing a more uniform weld, thereby improving the sealing effect of parallel seam welding.

[0048] Further preferably, the second end of the base 1 is provided with an annular protrusion 103 at a position corresponding to the periphery of the through hole 101, and the connecting thin plate 401 is fixedly connected to the top of the annular protrusion 103 by parallel seam welding, wherein the height of the annular protrusion 103 is 1.5±0.2 mm. By providing the annular protrusion 103, the welding points between the connecting thin plate 401 and the base 1 are concentrated in a smaller area, thereby reducing the requirements of the welding area on the sealing effect, forming a more precise seal, and further reducing the influence of welding stress on the overall sealing.

[0049] In the specific implementation process, a groove 104 is provided on the outer wall and / or inner wall of the bottom of the annular protrusion 103, specifically an annular groove, that is, the cross section of the annular protrusion 103 is a T-shaped or 7-shaped structure, thereby reducing the contact area between the annular protrusion 103 and the base 1 to reduce the heat dissipation during the parallel seam welding process. In addition, a chamfered structure is provided at the inner ring contour of the top of the annular protrusion 103, that is, the top of the annular protrusion 103 is an overall flared structure, so that the part of the metal seat 4 located below the connecting thin plate 401 can be more conveniently embedded in the tube perforation.

[0050] As a preferred embodiment, a sealing structure is provided in the vacuum chamber interface 102 to ensure the airtight connection between the base 1 and the vacuum chamber. Specifically, there is a step structure on the inner wall of the vacuum chamber interface 102, and the bottom wall of the step structure faces the first end of the base 1, and the sealing structure includes a sealing ring 8, a filter 9 and a clamping stud 10. A regular hexagonal through hole is opened in the center of the clamping stud 10, and an external thread is processed on the outside, and an internal thread that matches the external thread is processed on the side wall of the step structure. An annular groove is provided on the bottom wall of the step structure, and the first end of the sealing ring 8 is embedded in the annular groove, and the filter 9 covers the second end of the sealing ring 8. The clamping stud 10 is connected to the side wall thread of the step structure, and the filter 9 is clamped to prevent it from falling off. Among them, the filter 9 is mainly used to filter impurities in the measured environmental gas, and the regular hexagonal through hole on the clamping stud 10 is used to embed a wrench to tighten the clamping stud 10.

[0051] In this embodiment, a plurality of first through holes penetrating the metal seat 4 are provided on the metal seat 4, and a second through hole corresponding to the first through hole is provided on the circuit board 5, and the first through hole is coaxial with the corresponding second through hole. A metal column 402 is provided in the first through hole, and the metal column 402 is isolated and fixed to the hole wall of the first through hole by an insulating material. The first end of the metal column 402 is located in the through hole 101 and is connected to the MEMS structure 3 through a lead, and the second end of the metal column 402 is located above the circuit board 5 after passing through the second through hole, and the metal column 402 is fixed to the circuit board 5 by soldering, so that while realizing the electrical connection between the MEMS structure 3 and the circuit board 5, the sealing effect of the MEMS structure 3 can also be effectively guaranteed.

[0052] In this embodiment, the housing 2 is a rotating body structure with an opening at the first end, and the first end is sleeved on the second end of the base 1 and has an interference fit with the base 1. A square hole is opened at the second end of the housing 2, and two threaded holes are symmetrically distributed on both sides of the length direction of the square hole, so as to fix the J30 standard connector as the upper computer connector 7. It is worth noting that in the specific application process, the housing 2 and the base 1 are not limited to being fixedly connected by interference fit, and other connection methods, such as threaded connection, can also be used.

[0053] This embodiment also discloses a high vacuum MEMS sensitive structure packaging method, which mainly adopts the above-mentioned high vacuum MEMS sensitive structure packaging structure to achieve vacuum packaging of the MEMS sensitive structure. Specifically, the high vacuum MEMS sensitive structure packaging method includes the following steps:

[0054] Step 1, place the sealing ring 8 and the filter 9 on the bottom wall of the step structure in the vacuum chamber interface 102, and tighten the clamping stud 10 to prevent the filter 9 from falling off;

[0055] Step 2, thinning the edge of the metal base 4 to 0.1 mm to 0.15 mm to form a connecting thin plate 401, and then placing the metal column 402 in the first through hole of the metal base 4 and fixing it with an insulating material;

[0056] Step 3, attaching the MEMS structure 3 to the metal base 4 with the metal pillar 402, and connecting the pad on the MEMS structure 3 to the metal pillar 402 through wires;

[0057] Step 4, the connecting thin plate 401 on the metal seat 4 is welded to the annular protrusion 103 at the second end of the base 1 by parallel seam welding, so that the MEMS structure 3 is connected only to the side with the filter 9, isolating the gas influence on the other side;

[0058] Step 5, placing the circuit board 5 on the metal seat 4 through the metal pillar 402, and connecting the metal pillar 402 and the circuit board 5 by soldering, so that the circuit board 5 is electrically connected to the MEMS structure 3;

[0059] Step 6, connect the lead wire on the circuit board 5 with the upper computer connector 7 on the shell 2, and then connect and fix the first end of the shell 2 with the second end of the base 1 to assemble into a vacuum test gauge.

[0060] After completing the assembly of the vacuum test gauge, the end of the base 1 with the vacuum chamber interface 102 can be connected to the standard vacuum chamber through a clamp and tightened, and the host computer connector 7 is connected to the host computer through a connecting line to test the vacuum degree.

[0061] The above description is only a preferred embodiment of the present invention, and does not limit the patent scope of the present invention. All equivalent structural changes made by using the contents of the present invention specification and drawings under the inventive concept of the present invention, or directly / indirectly applied in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A high vacuum MEMS sensitive structure packaging structure, characterized in that: Including base, housing and vacuum gauge; The vacuum gauge comprises a MEMS structure, a metal seat and a circuit board, and the MEMS structure and the circuit board are respectively located at the upper and lower ends of the metal seat; The base is provided with a through hole, and the position of the first end of the base corresponding to the through hole is a vacuum chamber interface that can be connected to the vacuum chamber, the metal seat is fixedly connected to the second end of the base by parallel seam welding, and the metal seat covers the end of the through hole, and the MEMS structure is located in the through hole; The first end of the shell is fixedly connected to the second end of the base, and a placement cavity is formed between the shell and the base, the circuit board is located in the placement cavity, the second end of the shell is provided with a host computer connector, and the circuit board is electrically connected to the host computer connector; A connecting thin plate is provided on the side of the metal seat, and the connecting thin plate is fixedly connected to the second end of the base by parallel seam welding. The connecting thin plate and the metal seat jointly cover the end of the through hole to achieve extremely low gas permeability, ensure air tightness and improve stability. The thickness of the connecting thin plate is 0.1 mm to 0.15 mm. Considering that the metal seat itself has a large thickness, it is difficult for the edge of the metal seat to melt during parallel seam welding, and it is difficult to form a weld, which affects the sealing effect. By providing a connecting thin plate, the difficulty of edge melting caused by the thickness of the workpiece is reduced, thereby providing a more uniform weld, thereby improving the sealing effect of parallel seam welding; The second end of the base is provided with an annular protrusion at a position corresponding to the periphery of the through hole; The connecting thin plate is fixedly connected to the top of the annular protrusion by parallel seam welding; The height of the annular protrusion is 1.5±0.2mm. By setting the annular protrusion, the welding points between the connecting thin plate and the base are concentrated in a smaller area, thereby reducing the requirements of the welding area on the sealing effect, forming a more precise seal, and further reducing the impact of welding stress on the overall sealing.

2. The high vacuum MEMS sensitive structure packaging structure according to claim 1, characterized in that: The outer wall and / or inner wall of the bottom of the annular protrusion is provided with a groove to reduce heat dissipation during parallel seam welding.

3. The high vacuum MEMS sensitive structure packaging structure according to claim 1, characterized in that: A chamfered structure is provided at the inner ring contour of the top of the annular protrusion.

4. The high vacuum MEMS sensitive structure packaging structure according to claim 1, 2 or 3, characterized in that: A sealing structure is provided in the vacuum chamber interface to ensure airtightness of the connection between the base and the vacuum chamber.

5. The high vacuum MEMS sensitive structure packaging structure according to claim 4, characterized in that: A step structure is formed on the inner wall of the vacuum chamber interface, and the bottom wall of the step structure faces the first end of the base; The sealing structure comprises a sealing ring, a filter disc and a clamping stud, wherein a regular hexagonal through hole is opened in the center of the clamping stud, an external thread is processed on the outer side, and an internal thread matching the external thread is processed on the side wall of the step structure; An annular groove is provided on the bottom wall of the step structure, the first end of the sealing ring is embedded in the annular groove, the filter disc is covered on the second end of the sealing ring, and the clamping stud is threadedly connected to the side wall of the step structure and clamps the filter disc.

6. The high vacuum MEMS sensitive structure packaging structure according to claim 1, 2 or 3, characterized in that: The metal seat is provided with a plurality of first through holes penetrating the metal seat, the circuit board is provided with second through holes corresponding to the first through holes one by one, and the first through holes are coaxial with the corresponding second through holes; A metal column is provided in the first through hole, and the metal column is isolated and fixed to the hole wall of the first through hole by an insulating material; The first end of the metal column is located in the through hole and connected to the MEMS structure through a lead, the second end of the metal column passes through the second through hole and is located above the circuit board, and the metal column is fixed to the circuit board by soldering.

7. A high vacuum MEMS sensitive structure packaging method, characterized in that: The high vacuum MEMS sensitive structure packaging structure according to any one of claims 1 to 6 is adopted, and the high vacuum MEMS sensitive structure packaging method comprises the following steps: Place the sealing ring and filter on the bottom wall of the step structure in the vacuum chamber interface, and tighten the clamping studs to prevent the filter from falling off; The MEMS structure is attached to a metal base with a metal column, and the pads on the MEMS structure are connected to the metal column through wires; The connecting thin plate on the metal seat is welded to the annular protrusion at the second end of the base by parallel seam welding, so that the MEMS structure is connected only to the side with the filter and isolated from the gas influence on the other side; Place the circuit board through the metal pillars and place it on the metal seat, and connect the metal pillars and the circuit board by soldering; Connect the lead wire on the circuit board with the upper computer connector on the shell, and then connect and fix the first end of the shell with the second end of the base to assemble into a vacuum test gauge.

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